The demand for innovative and specialized portable electronic devices is ever increasing, and accordingly the design, packaging and functionality of electronic devices is constantly adapting and improving to meet the demand. Numerous devices employ two transmission lines for conducting differential signals within the device. However, with the increase in complexity and functionality of many devices, such as mobile phones, computers, personal digital assistants, personal navigation systems and the like, there is an increased need for a transmission line system that can handle differential signals in a multiplexed fashion. Moreover, in an electrical system that uses differential signaling and uses differential transmission lines to transport signals it is advantageous to have high common mode characteristic impedance between the transmission lines, while maintaining the desired differential mode characteristic impedance.
Unfortunately, systems having three or more transmission lines have a number of undesirable side effects, including adverse effects on the differential and common mode impedances of the transmission lines. In order to avoid the aforementioned adverse effects, some transmission line systems employ ground or power strips disposed between the transmission lines to retain the desired differential mode characteristic impedance results. Unfortunately, it is often the case that the presence of additional ground or power strips reduces the common mode impedance of the transmission lines, which is undesirable in a number of applications. Moreover, the addition of the ground and power strips increases the complexity, cost, and size of the package and restricts the environments in which it can be used.
As such, there is a need in the art for a transmission line system that can employ differential signaling using three or more transmission lines wherein any two of the three transmission lines exhibit roughly equal differential mode characteristic impedance while maintaining high common mode characteristic impedance.